Process of reclaiming rubber



Patented Feb. 2, 1932 f UNITED STATES ATENT OFFICE TALIAFERBO J". FAIRLEY, OF STERLINGTON, LOUISIANA, ASSIGNOBI, BY DIRECT AND MESNE ASSIGNMENTS, OF ONE-HALF TO W. 5. HUNTER AND ONE-HALF TO MARY P. HUNTER, BOTH OF SHREVEPORT, LOUISIANA PROCESS OF REGLAIMING RUBBER No Drawing.

The solvent material recovered by this treatment as a distillate or disillates are mainly the fraction up to 150 C., and from 150 C. to 17 0 (1; also the fraction from 170 to 190, as well as the fraction 190 to 250.

Glearly,'various.of the fractions may be used individually or may be blended, dependent upon the character of rubber employed, and it may be stated that my treatment has proven satisfactory in connection with crude or virgin rubber, vulcanized rubber, so-called hardrubber such as vulcanite and, in fact, to various rubber products as now manufactured. t

In carrying out the invention, I place the rubber to be treated or devulcanized in a suit able vessel or container, and cover it with an approprite' amount of the above mentioned solvent. In connection with the container, I may or may not use a reflux condenser and the process may proceed under ordinary atmospheric pressure or under vacuum. The advantage of a vacuum treatment may be briefly stated to be that the boiling point of V the solvent is lowered, so that it will be possible toheat the batch to boiling with the desirable resultant agitation.

' Where, however, the vacuum treatment is not employed, I subject the batch to a gentle heat and have determined that the most sat1s-.

factory temperature is one which is preferably below theboiling point of the solvent. Just what this temperature will be, of course, will vary in accordance with the nature of the solvent, as well as the rubber un-- der treatment, but it can be stated as somewhere below 175 C. and above 100 C. Of

course, it is possible that in some cases a tem- Application filed August 3, 1928.

perature below 100 would be satisfactory, but I have, in my experiments so far, not encountered any rubber which would go into solution in this solvent below this temperature. In this connection, it should be stated that the range of temperatures which I preferably employ, have been eminently satisfactory, because the rubber has gone into solution very rapidly and the time element is one of major importance in an operation of this character. The temperatures below 100 C. might, under these circumstances, be equally satisfactory, but the time required would be impractical from the standpoint of economic operation.

In heating the batch, a gentle heat is applied and thereafter the temperature is gradually raised and the rubber passes into solution rapidly, up to the desired temperature which I find it satisfactory to maintain. This temperature may, for instance, be 120 C. and in some cases 130 C. and in other cases as high as 150 C. I

The range of temperatures is important, since the residue to be obtained may be sticky and tacky and wholly unsatisfactory, unless with a particular rubber an appropriate temperature is employed and'this, as stated, I have found to be preferably one below the boiling point of the solvent.

When a test indicates that the rubber is dissolved, the neXt step is to remove therefrom the textile fibers, generally cotton fibers, and in order to reclaim these, the solution is preferably strained or filtered.

The textile fibers recovered have a marked degree of life and can be reused for many pursolution will work satisfactory in a great majority of cases.

The alkali which I have employed is preferably caustic soda, but other alkalis such as the and-this necessarily depends upon the-apparams, the nature of the material treated, andall of the other factors which are usual on which may, from time to time, specifically enter into the operation. Y The batch of solution and. alkali is now heated in such a manner as to evaporate or i drive off the solvent which, as stated in my former case, may be reclaimed and again employed, i

The temperatures to which this is conducted, of, course, will necessarily vary withthe boilingof the-solution,

usual manner.

- used in ubber ma u a ure- There remains then a a residue, con sisting of the rubber and the ma or port onof the alkali solution as well as some of the compounds;

' The rubber may be readily run; off from the topof the tank or still, or the caustic solution may; be withdrawn fromthe bottom,- as" desired, Preferably, however, the rubber is fwithdrawn, since by this step, .itv will not be, necessary to replace the caustic solution, except'insofar as theremay be any losses in thefproper level required. Alsothis will enjable the requiredconcentration to be main tained; I

v The rubber, as drawn ofi,is somewhat pla s: tie and contains a small proportion of alkali and the product is then treated to remove the.

alkali, 'asiby a'suitable washing treatment, as

., well known,

Thereafter, the rubber is subjecteclto drying after the, manner ofjanyvof a number of well known processes, such as direct heating, a uum drying, all of-wh ch are well known: in the art, and which areonly related to my invention, insofar as the drying oftheplastic mater al 1s. concerned.

free from tackiness. The product, may be mixed with crude rubber and milledin the By reason of'the treatment here outlined, namely,'the. heating of the solutionunder a temperature below'the boiling point of the solvent, and, the subsequent treatment and evaporation in the presence of an alkali, the; rubber product ultimately obtained is highly.

valuable,since.it is free from stickinessand tackiness, and can be dried to assume aicondition approaching crude rubber, in, that' 't.v possesses some elasticity with a very' slight plastic property.- 7

I claim 1. The process of treatingvulcanized rubher which comprisesmixing therubber vwith a distillate obtained by distilling a turpene wood fraction obtained from the direct distillation of wood in the presence of a clay having a catalytic action, and heating the massuntil the rubber goes intosolution, adding, an alkali solution, driving off the solvent by heating, and separating the rubber from the alkali to obtain a soft'rubber mass free from stickiness,- 1 I '1 I 2. The process oftreatingvulcanized rubber whichf comprises mixing-the r-ubben with adistillateobtained by fractionally distilling turpentine in the presence of a clay having a catalytic action, heating the mass untilthe rubber goes into solution, adding an alkali solution, driving olf the solvent by'heating, and separating the rubber from the alkali. to obtain a soft rubber mass free fromstickiness. 3; The process of treating vulcanized rub, her which comprises mixing the rubber; with a distillate comprising at least one-ofthe frac tions boiling below250-l obtained-by fractionally distilling turpentine. in the-presence one, clay having a catalytic action, heating the mass until the-rubber goes intosolution,

- 4;,- The processof treatingvulcanizedrub- 1 her which comprises mining the rubber with a distillate: comprising'the fractions boiling up to 190? Q; obtained by fractionally distillmglturpentine -in,the presence of a clay,

' having acatalytic action, heating themass to form ,asolution, addingan, alkali solution, I drivingiotf the solvent by heating, and separatingthe-rubber from the alkali toobtain a soft rubber; mass free from stickiness.

5. ,The process of; treating vulcanized rub-H her which comprises mixingtherubberawithi a distillate comprising at least one of the fractionsboiling below 25Q C. obtained byfr-ao, tionaglly distilling? turpentine .in the presence. of a. clay. having acatalytic action, heating the; massuntil [the rubber goes :into' solution,

I v strainingthe-solution, adding analkalisolu The resultant product is dry, elastic and:

ti ndriving ofii the solvent by heating, and separatinggthe rubber from the alkali to ,obtain a "soft rubber mass free from stickiness} 6. The,- process of: treating; vulcanized rubbeer; which comprisesmixingthe rubber witha distillate.,comprisingat least one of the, fractions boilingbelow250 C. obtained by fractionally distilling turpentine in thepresence of a clay havinga catalytic act-ion, heatingthe massiintil the rubber'goeslfinto solu-' tion, adding analkalisolution, driving offthersolvent by heating, separating the rub-. b'er fronnthe alkalitocbtainja soft rubber mass free from stickiness f and drying the rubber mass so obtained, v

In testimony whereof I have hereunto set. mr an v TALIA ERRQLJ.mitten 

